1. Field of the Invention
The present invention relates to a stabilized freeze-dried preparation of an etoposide derivative which is useful as an antitumor agent.
2. Statement of the Prior Art
4-O-( 2-Deoxy-2-dimethylamino-4,6-O-ethylidene-.beta.-D-glucopyranosyl)-4'-demet hyl-4-epipodophyllotoxin hydrochloride (hereafter abbreviated as etoposide-2-dimethylamino compound) is a derivative of antitumor agent, etoposide. The etoposide-2-dimethylamino compound is excellent in solubility which is a defect of etoposide and exhibits an antitumor activity (cf. U.S. Pat. No. 4,716,221).
However, the etoposide-2-dimethylamino compound is unstable in an aqueous solution, which makes storage over a long period of time difficult.
A pharmaceutical preparation obtained by merely dissolving the etoposide-2-dimethylamino compound in distilled water followed by freeze drying involves a drawback that when the compound is reconstituted with water, pH of its solution increases to cause precipitation of crystals.